The goal of this proposal is to study the production and biological roles of lipid mediators in models of inflammation and apoptosis, processes that are inherent components in pulmonary diseases. The four scientific projects bring together complementary approaches to investigate the regulation of eicosanoid production in macrophages during phagocytosis;and to identify unique lipid mediators produced by oxidants and during apoptosis, which act as signals for apoptotic cell recognition by phagocytes. The objectives include: 1) Investigating mechanisms of cPLA2 activation in macrophages during phagocytosis of microorganisms that engage specific pattern recognition receptors;determining the role of cPLA2 in the susceptibility to microbial infection;and studying mechanisms for cPLA2 inactivation by oxidants and caspases during phagocytosis. 2) Studying how the subcellular organization and formation of complexes of downstream enzymes involved in eicosanoid production by macrophages regulates production of eicosanoids from the cyclooxygenase and lipoxygenase pathways. 3) Determining if lyso- and oxidized-phospholipid mediators are produced by apoptotic cells;and elucidating their mechanism of externalization and role as signals for the recruitment, recognition and engulfment by phagocytes. 4) Structural characterization by mass spectrometry of lipid mediators produced from cholesterol, plasmalogen and phosphatidylserine in response to oxidant exposure and during apoptosis. Novel mass spectrometry approaches will be developed to image these lipid mediators in pulmonary tissues. This program brings together investigators with diverse expertise in cell biology, biochemistry, enzymology and structural biology. Multidisciplinary approaches will be used to provide information about the structural identity of lipid mediators, the molecular mechanisms involved in their production, and their biological roles.